promise
Promises/A+ implementation for Python
Decision gist · record as of 2026-08-14
Yes-with-conditions. The package is stable (MIT, no known vulnerabilities, 367 GitHub stars) but dormant since 2019. Install only if you are maintaining legacy code that already uses promise or integrating with a framework that requires it. For new projects, use Python's native async/await and asyncio instead.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- High install friction due to source-only distribution (promise-2.3.tar.gz).
- Maintenance is dormant—last release was 2019-12-18 and last commit 2024-07-09, with no active development signals.
License · maintenance · safety
MIT (permissive) — MIT license (permissive) places no restrictions on use, modification, or distribution. Safe for commercial and open-source projects.
last release 2019-12-18 (2431 days) · last repo commit 2024-07-09 · 367 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 3,280,496 downloads/mo, #2,676 on PyPI
Alternatives
Verify before relying
from promise import Promise
promise = Promise(lambda resolve, reject: resolve('RESOLVED!'))
result = promise.then(lambda value: print(value))- Whether promise.get() method exists and how it blocks/retrieves resolved values (shown in docs but not formally specified)
- Python 3.9+ compatibility—classifiers list only up to 3.8; current support unclear
- Whether this package is maintained or if a modern alternative is recommended for new projects
What it is and what it does
Promise is a Python implementation of the Promises/A+ specification, a standard for handling asynchronous operations through chainable callbacks. It lets you wrap async work in a Promise object, resolve or reject it with a value, and attach handlers via .then() and .catch() that execute when the promise settles. The library supports composing multiple promises (Promise.all, Promise.for_dict) and wrapping existing futures.
The package has no runtime dependencies and works with Python 2.7 through 3.8 (and PyPy). It is designed to be a readable, performant alternative to raw callbacks for async patterns in Python, though modern Python now has native async/await syntax and asyncio, which may be preferable for new code.
Use it for
- Wrapping callback-based async operations (e.g., I/O) in a chainable Promise interface for cleaner control flow
- Composing multiple async tasks with Promise.all() to wait for all to complete before proceeding
- Converting Python Futures into Promises for interoperability with promise-based libraries or frameworks
- Building promise-based libraries or frameworks that need a standard async abstraction layer
- Handling rejection and error propagation through .catch() in async workflows without explicit try/except nesting
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes-with-conditions.
The package is stable (MIT, no known vulnerabilities, 367 GitHub stars) but dormant since 2019. Install only if you are maintaining legacy code that already uses promise or integrating with a framework that requires it. For new projects, use Python's native async/await and asyncio instead.
Install
promise on PyPI
Before you install
High install friction due to source-only distribution (promise-2.3.tar.gz). Maintenance is dormant—last release was 2019-12-18 and last commit 2024-07-09, with no active development signals.
License in practice
MIT license (permissive) places no restrictions on use, modification, or distribution. Safe for commercial and open-source projects.
Quickstart
from promise import Promise
promise = Promise(lambda resolve, reject: resolve('RESOLVED!'))
result = promise.then(lambda value: print(value))Verify before relying
- Whether promise.get() method exists and how it blocks/retrieves resolved values (shown in docs but not formally specified)
- Python 3.9+ compatibility—classifiers list only up to 3.8; current support unclear
- Whether this package is maintained or if a modern alternative is recommended for new projects
Package facts
| License | MIT permissive |
| Python support | Not specified |
| Install friction | High. Source build required |
| Runtime dependencies | None |
| Maintenance | Dormant 2,431 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 3,280,496 / month, #2,676 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableIntended Audience :: DevelopersLicense :: OSI Approved :: MIT LicenseProgramming Language :: Python :: 2Programming Language :: Python :: 2.7Programming Language :: Python :: 3Programming Language :: Python :: 3.3Programming Language :: Python :: 3.4Programming Language :: Python :: 3.5Programming Language :: Python :: 3.6Programming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: Implementation :: PyPyTopic :: Software Development :: Libraries |
Evidence: promise-2.3.tar.gz
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